总结三种Shell脚本编程中避免SFTP输入密码的方法
最近编程中用到sftp上传文件，且需要用crontab预设定时上传事件。而sftp不同于ftp，没有提供选项如 -i 可以将密码直接编码进程序。使用sftp指令，会自动请求用户输入密码。
总结一下可以避免sftp输入密码的三种方式：
1. lftp方式
#!/bin/sh
HOST=172.16.2.X
USER=kg_sftp
PASS=tnzk4a7w
echo "Starting to sftp..."
lftp -u ${USER},${PASS} sftp://${HOST} <
2. expect方式
Expect是一个免费的编程工具语言，用来实现自动和交互式任务进行通信，而无需人的干预。
要使用expect需要预先安装tcl这个东西,然后再安装expect包。
tcl: http://prdownloads.sourceforge.net/tcl/tcl8.4.16-src.tar.gz
expect: http://sourceforge.net/projects/expect/files/Expect/5.45/expect5.45.tar.gz/download
例子：
#!/usr/local/bin/expect -f
#<---insert here your expect program location
#procedure to attempt connecting; result 0 if OK, 1 elsewhere
proc connect {passw} {
expect {
"(yes/no)?" {send "yes/r";exp_continue} #第一次使用SFTP时候会要求输入yes/no
"password:" {send "$passw/r" #自动输入密码
expect {
"sftp*" { #检测返回sftp>
return 0
}
}
}
}
# timed out
return 1
}
#read the input parameters
set user [lindex $argv 0]
set passw [lindex $argv 1]
set host [lindex $argv 2]
set location [lindex $argv 3]
set file1 [lindex $argv 4]
#puts "Am citit:/n";
#puts "user: $user";
#puts "passw: $passw";
#puts "host: $host";
#puts "location: $location";
#puts "file1: $file1";
#check if all were provided
if { $user == "" || $passw == "" || $host == "" || $location == "" || $file1 == "" } {
puts "Usage: /n"
exit 1
}
#sftp to specified host and send the files
spawn sftp $user@$host
set rez [connect $passw]
if { $rez == 0 } {
send "cd $location/r"
set timeout -1
send "put $file1/r"
#send "ls -l/r"
#send "quit/r"
#send "mkdir testsftp/r"
send "quit/r"
expect eof
exit 0
}
puts "/nCMD_ERR: connecting to server: $host!/n"
exit 1
0
expect也可以用两种形式调用
1 ./my.exp $usr $pwd $host $local $file
2. 代码中直接插入
expect<
...
!
3. (推荐)生成密钥对
因为这种方式不用把密钥卸载程序里,所以更安全
第一步：生成密匙对，我用的是rsa的密钥。使用命令 "ssh-keygen -t rsa"
[user1@rh user1]$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/user1/.ssh/id_rsa):
Created directory '/home/user1/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/user1/.ssh/id_rsa.
Your public key has been saved in /home/user1/.ssh/id_rsa.pub.
The key fingerprint is:
e0:f0:3b:d3:0a:3d:da:42:01:6a:61:2f:6c:a0:c6:e7
[email protected]
[user1@rh user1]$
生成的过程中提示输入密钥对保存位置，直接回车，接受默认值就行了。接着会提示输入一个不同于你的password的密码，直接回车，让它空着。
当然，也可以输入一个。(我比较懒，不想每次都要输入密码。) 这样，密钥对就生成完了。
其中公共密钥保存在 ~/.ssh/id_rsa.pub
私有密钥保存在 ~/.ssh/id_rsa
然后改一下 .ssh 目录的权限，使用命令 "chmod 755 ~/.ssh"
[user1@rh user1]$ chmod 755 ~/.ssh
[user1@rh user1]$ chmod 755 ~/.ssh
之后把这个密钥对中的公共密钥复制到你要访问的机器上去，并保存为
~/.ssh/authorized_keys
[user1@rh user1]$ scp ~/.ssh/id_rsa.pub rh1:/home/user1/.ssh/authorized_keys
user1@rh1's password:
user1@rh1's password:
id_rsa.pub 100% 228 3.2MB/s 00:00
[user1@rh user1]$
之这样就大功告成了。之后再用ssh scp sftp 之类的访问那台机器时，就不用输入密码
了，用在script上更是方便。